Vacuum truck system

ABSTRACT

An endless conveyor mechanism for holding one or more webs and/or other parts on a rigid surface while they are conveyed along a rectilinear path comprises a plurality of rigid truck members arranged to move in a closed path one portion of which is the rectilinear path through which the web or other parts are to be moved, and means for moving said trucks so that during the time they are moving in said trucks so that during the time they are moving in said rectilinear path they are held in abutment so that their web-supporting surfaces combine to form, in effect, a single rigid surface on which the web or other parts are held by vacuum as they are moved through said path. The driving mechanism for the truck members brings the trucks into tight abutment at the beginning of the rectilinear path, then advances said trucks in butted relation through said path at a controlled rate, while at the same time accommodating for slight tolerances in individual truck dimensions, and then controls the movement of the trucks into the return portion of their path in such a way as to prevent them from bumping together and becoming damaged.

United States Patent (72 Inventors Stanley R. Schleven Webster; GeraldA. Sampson, Perilleld, both of NY. [211 App]. No. 874,324 [22] FiledNov. 5, 1969 [45] Patented Nov. 9, 1971 [73] Assignee Eastman KodakCompany Rochester, N.Y.

[54] VACUUM TRUCK SYSTEM 10 Claims, 1 1 Drawing Figs. [$2] 'U.S. Cl226/95, 104/167, 198/129 [51] Int. Cl B65h 17/28 [50] Field of Search226/95. 170. 173; 104/166, 167, l62;93/93; 271/68; 254/134.5; 198/129[56] References Cited UNITED STATES PATENTS 2,789,683 4/1957 Stahl104/167 X 3,236,162 2/1966 Reist 271/68 X Primary Examiner-Allen N.Knowles Assistant Examiner-Gene A. Church AnorneysWilliam T. French,Robert F. Crocker and Karl T.

Naramore ABSTRACT: An endless conveyor mechanism for holding one or morewebs and/or other parts on a rigid surface while they are conveyed alonga rectilinear path comprises a plurality of rigid truck members arrangedto move in a closed path one portion of which is the rectilinear paththrough which the web or other parts are to be moved, and means formoving said trucks so that during the time they are moving in saidtrucks so that during the time they are moving in said rectilinear paththey are held in abutment so that their web-supporting surfaces combineto form, in effect, a single rigid surface on which the web or otherparts are held by vacuum as they are moved through said path.

The driving mechanism for the truck members brings the trucks into tightabutment at the beginning of the rectilinear path, then advances saidtrucks in butted relation through said path at a controlled rate, whileat the same time accommodating for slight tolerances in individual truckdimensions, and then controls the movement of the trucks into the returnportion of their path in such a way as to prevent them from bumpingtogether and becoming damaged.

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STANLEY R. SCH/EVEN GERALD A. SAMPSON lNvlz'NTORs WQM ATTORNE sPATENTEDN 9 SHEET a []F 9 STANLEY R SCH/EVEN GERALD A. SAMPSON INVENTORSA rromvrs PATENTEUunv 9 IHTI SHEET 3 [IF 9 STANLEY R. SCH/EVEN GERALD ASAMPSON v INVENTORS A TTORNEYS PATENTEmmv 9 IBYI SHEET [1F 9 mm .m EPR Emun WM m n M A Em L SHEET 5 [IF 9 PATENTEDuuv 9 |97| STANLEY/Z SCH/EVENGERA 1.0 A SAMPSON IWENTORS A r romve Vs &

Q STANLEY R. SCH/EVEN GERALD A. SAMPSON mvmvmxs SHEET 7 [IF 9 A W W 9mmWNN WV. A TTOR/VEYS PATENTEUNUV 9 911 PATENTEDNOV 9 l97| SHEET 8 OF 9STANLEY R. SCH/EVEN GERALD A SAMPSON INVENTORS III/IA ATTORNEYS SHEET 9[IF 9 PATENTEDNUV 9 I97! Mam VACUUM TRUCK SYSTEM The present inventionrelates to an endless conveyor mechanism, and particularly to a vacuumconveyor mechanism for continuously conveying a web, or two or more websand/or other discrete elements along a rectilinear path at a controlledrate of speed while holding them on a rigid surface in predeterminedoverlying relation.

Endless perforated belts sliding over a stationary vacuum manifold havebeen used for feeding a web and other materials individually in a flatcondition through a rectilinear pathof limited length. However, beltconveyors of this type involve problems relating to friction, dustingand stretching, particularly in situations where the plane of movementis substantially long so that relatively long belts are required. Avacuum drum is another well-known way of conveying a web, or webs, butit has the disadvantage of differential length when conveying overlyingwebs and is not compatible with associated apparatus which requires thatthe webs be supported flatwise in a plane dun'ng conveyance through acertain portion of their path of movement. Also, a vacuum drum is notsatisfactory for conveying discrete articles which are flat and cannotbe bent to conform to the drum surface.

The primary object of the present invention is to provide a vacuumconveyor mechanism having the capabilities of known endless belt systemsso far as feeding a web or other materials in a rectilinear path, buthaving none of the abovenoted disadvantages thereof. I

Another object is to provide a conveyor mechanism of the type set forthwherein the conveyor path comprises a plurality of rigid truck membersarranged to move in a closed path one portion of which is therectilinear path through which the web or other materials are to bemoved, and means for moving said trucks so that during the time they aremoving in said rectilinear path they are held in abutment so that theirwebsupporting surfaces combine to form, in effect, a single rigidsurface on which the web or other materials are held by vacuum as theyare moved through said path. 4

A further object is to provide a conveyor mechanism of the type setforth including a driving mechanism for the truck members which bringsthe trucks into tight abutment at the beginning of the rectilinear paththrough which the articles are to be fed, then advances said trucks inbutted relation through said path at a controlled rate, while at thesame time accommodating for slight tolerances in the individual truckdimensions, and then controls the movement of the trucks into the returnportion of their path in such a way as to prevent them from bumpingtogether and becoming damaged.

A still further object is to provide a conveyormechanism of the type setforth including means for keeping the vacuumporting region between thestationary vacuum manifold and the individual trucks free of dustparticles.

The novel features that we consider characteristic of our invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its methods ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of specificembodiments when read in connection with the accompanying drawings inwhich:

FIG. 1 is a side elevational view of a representative composite partwhich can be assembled on the present endless vacuum conveyor system;

FIG. 2 is a schematic view showing how the present vacuum conveyorsystem is used to assemble a plurality of webs in a given superposedrelation to form the composite part shown in FIG. 1;

FIG. 3 is a front elevation of a vacuum truck system constructed inaccordance with a preferred embodiment of the present invention;

FIG. 4 is an enlarged transverse sectional view taken substantially online [*4 of FIG. 3;

FIG. 5 is a bottom plan view of one of the vacuum trucks;

FIG. 6 is an end view of the vacuum truck system looking from theleading end thereof, and with the trucks rising from the return path tothe leading end of the top straight section omitted for purposes ofclarity;

FIG. 7 is an isometric schematic view of the drive mechanism for thediflerent driving elements of the vacuum truck system;

FIG. 8 is an isometric view, on an enlarged scale, of the gear drivesfor the metering screws;

FIG. 9 is a side elevational view, partly in section, showing thefloating mounting for the leading metering screws and their drives;

FIG. 10 is an end view of the leading metering screws and their drivestaken substantially on line 10-10 of FIG. 9; and

FIG. 11 is a partial top plan view of a portion of the top straightsection of the vacuum truck system with certain trucks omitted and withthe bed of one truck omitted, for the purposes of clarity.

While this vacuum conveyor mechanism was developed primarily forassembling a plurality of webs and discrete pieces together on acontinuous motion assembly machine, and will be described in thiscapacity for disclosure purposes, it will be obvious that its usefulnessis not limited to such an application. It is necessary that the variouswebs and/or pieces be assembled in nearly perfect registration. Thisrequires that the position and speed of each web and/or piece be wellcontrolled and it is necessary, or desirable, that the length of allwebs be equal.

In this invention an appropriate number of individual elements, referredto hereinafter as trucks, are forced to travel in a prescribed closedpath. This is accomplished by having followers attached to each truckengage with a cam path. The path is such that a top straight section ofsuitable length is established through which the webs and/or pieces areto be moved at a controlled rate of speed while being supported on thesurface of a plurality of the trucks. A semicircular section at each endof the top straight section connects to a lower return path. This ineffect defines an endless elongated loop.

A tendency drive located at the beginning of the top straight sectionforces each truck into butted relationship to the one immediately aheadof it. Two counterrotating screws are located near the downstream end ofthe top straight section and partial nuts are attached to the undersideof each truck. As each truck reaches the end of the top section thepartial nuts engage with the screws. Thus, the screws serve as ametering device for the truck system across the straight top section.

In the event the number and weight of the trucks between the tendencydrive and the metering screws is too great for the tendency drive toadequately handle, then a second pair of metering screws, driven at thesame rate of speed as the firstmentioned pair, may be located closer tothe tendency drive to positively feed the trucks to the first-mentionedpair of metering screws. This second pair of metering screws will bemounted to move to and from the first-mentioned pair of metering screwsin the direction of movement of the trucks and will be biased towardsaid first-mentioned pair of metering screws to accommodate for anyslight dimensional tolerances in the individual trucks. As each truckleaves the metering unit, or the top straight section, it engages with apair of driven wheels which press against the underside of the truckforcing them against the outer face of the semicircular cam pathsection. In this manner, the trucks are held in spaced-apart relationand kept from rolling freely downward to the return section and bangingtogether and becoming damaged. Similar driven wheels are used at the endof the return section to carry each truck up to the top straight sectionand into engagement with the tendency drive.

Vacuum is used to assure retention of individually applied webs or otherparts and to prevent them from slipping on the trucks and relative toeach other as they move across the top straight section. To this end itis desired that vacuum be applied to different regions of the topsurface or bed of the trucks at different times and for differentintervals of time as the trucks move along the top straight section. Twoor more porting holes are laterally spaced through the lower face(called the porting face) of each truck. Each of these holes isconnected by appropriate coring to a different region of the bed of eachtruck. A stationary vacuum manifold is located so that the porting facesof the trucks move in close proximity to the porting face of themanifold. Longitudinal slots in the porting face of the manifold arealigned with the porting holes in the trucks. Thus, as each truck movesalong the top straight section, vacuum is applied to the various regionsof the truck beds, the timing being controlled by the location andlengths of the slots in the porting face of the vacuum manifold.

The clearances between the porting faces of the trucks and the vacuummanifold is so close that if foreign particles, such as dust enters thisspace, damage may occur. Entry of such foreign particles into thisregion is prevented in the following manner. The porting faces of boththe trucks and manifold are somewhat larger than required to accomplishthe vacuum porting. In the region surrounding the vacuum slots on thevacuum manifold, means are provided to supply clean air under pressurein a quantity larger than that required to make up leakage into theporting area. This last-mentioned means comprises porous plastic insertsin a compressed-air plenum which essentially surrounds the vacuum slotsin the manifold.

The function and utility of a conveyor mechanism constructed inaccordance with the present invention will be more readily understood ifthe problem of assembling a particular composite part made up of aplurality of individual components joined together in a certainsuperposed relation is considered. Referring to FIG. I, suppose thecomposite part to be assembled comprises a first rectangular sheet 10, asecond rectangular sheet 11 overlapping sheet and a third rectangularsheet 12 overlapping sheet 11. These three sheets are held in properoverlapping relation by heat seals 13 and 14. A narrow strip of material15 extends across the top of sheet 11 and is fastened thereto by twoheat seals 16 and 17. The formation of these heat seals depends upon thesheets being either coated with suitable heat activated adhesive, ordepends upon the sheets themselves being composed of a thermoplasticmaterial which will soften sufficiently to adhere to one another.

A composite part of this type can be assembled continuously by bringingfour continuous webs of material of the proper width into the desiredoverlapping relationship in succession and making the heat seals to holdthem in the desired relation. As shown in FIG. 2, this may be done byfeeding webs 10' and 11' from supply rolls in the desired overlappingrelation onto the upper reach of an endless conveyor, indicatedgenerally at 20, and moving to the right, looking at FIG. 2. After thewebs l0 and 11 are fed onto the conveyor, they pass beneath aheat-sealing roller 21 which makes the seal 13. A continuous web 15' isthen fed from a supply roll onto the top of the web 11 and the heatseals 16 and 17 are made by passing under a pair of transversely spacedheat seal rollers 22, only one of which is shown in FIG. 2 but both ofwhich are shown in FIG. 4. Next, a web 12 is fed from a supply roll intooverlapping relation with web 11 and the heat seal 14 is made as thewebs pass under heat sealing roll 23. After the continuous strip ofoverlapping webs I0, ll, 12' and 15, leave the conveyor they may passthrough a chopping mechanism, not shown, which successively chops thecomposite strips into composite parts of suitable width having a sideelevation cross section like that shown in FIG. I. It should be pointedout that instead of the strip of material 15, a discrete part could beapplied to the top of sheet 11 by a single or double heat seal. Thiswould necessitate replacing the roll of web material 15 in FIG. 2 with ahopper of discrete parts and from which hopper the discrete parts wouldbe deposited on the top of web 11 at specified intervals and be heatsealed in place by passing under sealing rollers 22.

It will be understood that the assembly of a plurality of webs and/ordiscrete parts in the manner described requires a conveyor which willserve to convey the several parts continuously and at a given rate ofspeed over a rectilinear path of considerable length. Also, the conveyormust hold the parts in a predetermined superposed relation until theyare sealed together, and it must support the parts on a rigid surface sothat the necessary operations, e.g., sealing, can be performed on thewebs. Using the novel method of holding a plurality of parts inoverlying relation on a given surface as described in copendingapplication Ser. No. 841,888, filed July 15, 1969, a vacuum conveyor canbe used to transport the webs 10', 11', I2, and 15' over a rectilinearpath. In accordance with the invention disclosed in the above-notedapplication, the sheet 10 (FIG. 1) or the web 10 (FIG. 2) is providedwith one or more holes 25 through which a vacuum applied to the lowerface of sheet 10, or web 10' can act to hold the sheet 11 or web 11' inplace on top of the web 10' at least until the seal 13 is made.Likewise, the sheet 11, or web 11, is provided with a plurality of holes26 extending thereacross through which a vacuum can act to hold the web15' down onto the top of web 11'. As disclosed in the above-notedcopending application, the holes 25 and 26 can be replaced bymoon-shaped slits which will provide hinged fiaps which will pull downupon the application of a vacuum and provide a hole through which thevacuum can act on the part above. In this instance the bed of theconveyor aligned with such moon-shaped slits would be recessed to allowthe hinged flap to be pulled down out of the plane of its part by thevacuum.

Having thus set forth a particular assembly of parts which it is desiredto perfon'n in a continuous manner and at a known rate of speed, avacuum conveyor mechanism constructed in accordance with a preferredembodiment of the present invention for accomplishing this end will nowbe described. Referring to FIGS. 2, 3, and 4, this conveyor mechanismcomprises a pair of laterally spaced cam tracks 30 which define anendless path consisting of a substantially long, straight upper section32 which is parallel to the rectilinear path along which the parts areto be conveyed, a return portion 33 which is below and parallel to theupper straight section 32, and two semicircular portions 34 and 35connecting the upper and return portions. As shown in FIG. 4, each track30 consists of a rail 37 fastened by bolts 39 to a support member 41extending transversely beneath the tracks. Fixed to the outside face ofeach rail is a retainer member 43 having an inturned arm 45 spaced fromthe top of the rail to form therewith a channel.

An appropriate number of individual elements, referred to hereinafter astrucks 47, are forced to travel in the closed path defined by said camtracks. To this end, each truck 47, which is rectangular in shape asshown, has four rollers 49 (FIG. 5) attached thereto which rotatablyengage the tops of the rails 37. The retainer members 43 associated withthe rails prevent the rollers from jumping off the rails. Each truck 47has a flat top or bed 51 which extends across the tracks 30 by an amountsuch that they will define a portion of the rectilinear path throughwhich the parts are to be conveyed as the trucks move along the straightupper section 32 of the cam tracks 30. As will be clear from FIGS. 4 and11, the long dimension or length of each truck bed extends transverselyof the conveyor path and is substantially equal to the length of thecomposite part to be assembled.

A tendency drive located at the beginning of the top straight section ofthe cam tracks 30 forces each truck into butted relationship with theone immediately ahead of it. As clearly shown in FIGS. 3, 6 and 7, thistendency drive comprises two pairs of friction drive rolls 55 and 57arranged in tandem at opposite sides of the conveyor to drivingly engagethe vertical sidewalls 59 of each truck as it moves into the straightsection. The drive roll 55 on the front side of the conveyor, the rightside of FIG. 6 and the side shown in FIG. 3, is mounted on a verticalshaft 61 supported in bearings 63 and driven by a belt 65 from a motor Mengaging pulley 66. For sake of clarity, the motor M and belt 65 havebeen omitted from FIG. 6. The drive roll 55 at the back of the conveyoris fixed to the end of a vertical shaft 67 supported in bearings 68 anddriven by a belt 69 from a motor M The drive roll 57 at the front of theconveyor is fixed to a vertical shaft 70 which is directly driven by apancake type motor M The companion drive roller 57 at the back of theconveyor is fixed to the end of vertical shaft 71 which is directlydriven by a second pancake type motor M The only reason why differenttypes of motor drives are used for the two pairs of drive rolls 55 and57 is because of the space limitations imposed by the proximity ofvertical shafts on which these rolls are mounted.

The purpose of the first pair of drive rolls 55 is to engage each truck47 as it reaches the beginning of the top straight section and move itinto abutment with the truck immediately ahead of it so that the topsurface or beds 51 of the trucks will in effect combine to form a singlerigid surface as the trucks move along the straight section 32 of theconveyor. The purpose of the second pair of drive rolls 57 is to advancea series of trucks in butted relation until they are engaged by apositive metering drive which will be described hereinafter. This meansthat the drive rolls 57 must be capable of doing more work than driverolls 55 since the rolls 57 may be pushing a plurality of trucks alongthe straight section, whereas drive rolls 55 are moving only one at atime. However, since driving rolls 55 must move each approaching truckinto abutment with the one ahead of it before the trucks are engaged bydrive rolls 57, this means drive rolls 55 should tend to drive eachtruck slightly faster than they will be driven by dri've rolls 57. Toachieve these two ends the drive rolls 57 have a wider driving face thanthe drive rolls 55, thus giving them more driving power, and the motordrives to drive-rolls 55 is preferably made slightly faster than thoseto the drive rolls 57.

Two pairs of counterrotating driving screws 75 and 76 are coaxiallylocated in tandem downstream of the tendency drive rolls 55 and 57. Eachpair of screws 75 and 76 has the same thread pitch and are driven at thesame speed by a suitable drive means. As shown in FIGS. 7 and 8, thisdrive means may comprise a motor M connected through a gear box 78 to adrive shaft 79 which is in turn connected through a gearbox 80 to asecond drive shaft 81. Through another gearbox 82 shaft 81 is connectedto a shaft 83, on which the drive gear 84 for the pair of screws 76 islocated, and is also connected to another drive shaft 85 on which thedrive gear 88 for the pair of screws 75 is located,see FIG. 8. The geardrives for the two pairs of screws 75 and 76 is very similar and will bedescribed in detail hereinafter. In FIG. 7 these gear drives are shownmerely as boxes 75' and 76' because of the small scale of this FIG. Atthis point it will suffice to say that the gearing between each pair ofdrivescrews and the motor M is such that they will be rotated at thesame speed and their speed of rotation in conjunction with the pitch oftheir threads will determine the speed at which the trucks are movedalong the straight section of the conveyor path.

A pair of partial nuts 90 are attached to the outside of each truck inany suitable manner, e.g., by welding, and have threads which arecomplimentary to those of the screws 75 and 76, see FIGS. 4 and 5. Aseach truck 47 reaches the first pair of screws 75 the partial nutsengage with the screws so that from thereon the trucks are fedpositively along the top straight section 32 at a continuous ratedetermined by the speed of rotation of the screws and the pitch of theirthreads. It is for this reason that it is imperative that the tendencydrive rollers 55 and 57 bring the trucks into butted relation before,and hold them in such relation up until the time that, the trucks arepositively meshed with the driving screws 75. It will thus be seen thatthe drivescrews 75 and 76, alongwith the partial nuts on each truck,serve as a metering device for that portion of the truck system movingalong the top straight section 32 of the conveyor path. As shown inFIGS. 4 and 10, a stationary guide member 92 extends longitudinally ofthe top straight section and the inside edges of the partial nuts 90 oneach truck engage the longitudinal edges of this guide member, as shownat X in FIG. 4, to maintain the trucks in a given path as they movealong the top straight section of the conveyor path.

For the most part, the gear drives for the two pairs of metering screws75 and 76 are alike and differ primarily in that the screws 75 aremounted to move axially toward and from the screws 76 to accommodate forslight manufacturing tolerances in the width of the individual trucks aswill be hereinafter described. Referring to FIG. 8, the gear drive forthe screws 76 will be described. Although not shown in detail, thescrews 76 are rotatably mounted in fixed bearings and one screw has asmall gear 95 fixed to the end of a shaft thereon, while the other has alike small gear 96 fixed to the end of a shaft thereon. Small gear 95 isdriven from drive gear 84 through a first intermediate gear 97 which inturn drives a second intermediate gear 98 corresponding to-gear 97.Coaxially arranged relative to, and adjustably connected to, gear 98 isa third gear 99 which drives the small gear 96 at the same speed as thesmall gear 95 but in an opposite direction. The double gear arrangement98 and 99 is used to permit a limited arcuate adjustment of the tworelative to one another for the purpose of timing the two screws 76, andafter which adjustment the two are pinned together to rotate as one.Since such timing adjustments of coaxial gears are well known, thedetails of the structure permitting such adjustment has not beenillustrated.

Coming now to the gear drive for the pair of screws 75, it will be seenthat it is essentially the same as that for screws 76 and includesintermediate gear 97' driven from drive gear 88 which is the same sizeas drive gear 84 and driven by shaft at the same speed and in the samedirection as the drive gear 84. As before, intermediate gear 97' drivesa small gear 95 fixed to one of the screws 75 and also drives a secondintermediate gear 98' adjustably connected to a like coaxial gear 99'which drives the second screw 75 through the small gear 96. Thecorresponding gears of the drives for the two pairs of screws 75 and 76are of the same size and are driven in the same direction. They are infact all helical gears for the purpose of providing a smooth drive,although they have been illustrated as spur gears for purposes ofclarity and simplicity.

If the distance between the tendency drive rolls 55 and 57 and thesecond set of metering screws 76 is not so great that the number oftrucks 47 accumulating between these two drives does not overload thetendency drive then there is really no need for the first pair ofdrivescrews 75. However, where the length of the top straight section ofthe conveyor is required to be so long that as many as 20 or 30 trucks47 might accumulate between the tendency drive and the second pair ofscrews it has been found that the weight of the trucks that the tendencydrive must push along in butted relation before they become engaged bythe metering screws 76 may induce a load on the tendency drive so greatthat it will fail to keep the trucks butted up to the time they engagethe metering screws 76. For this reason the second set of meteringscrews 75 have been provided close to the tendency drive. Since thenumber of trucks 47 accumulating between the two sets of metering screws75 and 76 is significant, and the widths of the individual trucks mayvary from a given value despite the most rigid manufacturingspecifications, some means must be provided to accommodate for atolerance variation in the truck widths in order that the partial nutson a series of trucks along the top straight portion will properlyengage the two sets of screws 75 and 76 at the same time. For example,if each truck width was only 0.001 inch oversize, then if there were 30trucks in the straight portion engaging the two sets of metering screwsthen the last truck engaging the metering screws 75 would be 0.030 inchout of phase with the lead thread of the metering screws 76 and wouldnot properly engage it. To accommodate for such a condition, and toinsure each truck properly engaging the lead thread of the first set ofscrews 75 and moving along both sets of screws without binding, thefirst set of screws 75 are mounted so as to be capable of a limitedcoaxial movement and are biased toward the second pair of screws 76.

To this end the first pair of metering screws 75 and the drive gears 88,-99' are mounted for limited axial movement as shown in FIGS. 8, 9 and10. As shown in FIGS. 10 and 9, each of the gears 88, 95 99 and theleading end of each of screws 75 are rotatably supported in the uprightarm 100 of a bearing support 101. The rear ends of the screws 75 arejournaled in bearings 102 carried by a second bearing support 103. Thetwo bearing supports 101 and 103 are tied together by a pair oftransversely spaced tie rods 104 fixed to each of the bearing supports,as by means of a set screw 105, as shown most clearly in FIG. 9. Tierods 104 are slidably mounted in bushings 106 in arms 107 extendingdownwardly from a horizontal stationary supporting plate 108 attached tothe horizontal top 109 of the frame 110 of the apparatus in any suitablemanner, as by bolts 111. So that the drive from drive gear 88 to driveshaft 85 will be maintained during limited axial movement of themetering screws 75 and their associated drive gears, drive gear 88 isconnected to shaft 85 through a spline 113 on the end of shaft 85engaging internal teeth 114 formed in the wall of a bore 115 extendingcoaxially through the hub M6 on drive gear 88. The drive gear 88 isjoumaled in bearing support 101 by a bearing 117. Fixed to the undersideof plate 118, and located intermediate the tie rods 104, is a downwardlyextending clevis 119 to which is pivoted, at 220, to the end of aplunger of a double-acting air cylinder 221 whose other end is pivotedat 222 to a second clevis 223 fixed to a vertical leg 224 of the machineframe 110. It will be appreciated that this floating mount for themetering screws 75 and their gear drive provides for a limited axialmovement thereof relative to the metering screws 76 which is sufficientto accommodate for any cumulative error in the spacing between thepartial nuts of the row of trucks engaging the two sets of screws whichmight result from variations of the manufacturing tolerances in thewidths of the individual trucks, and thereby insures a proper meshingbetween the nuts of the trucks and each set of metering screws at alltimes during the travel of a plurality of trucks across the top straightsection of the conveyor path.

As each truck 47 leaves the metering screws 76, it engages with a pairof driven wheels 120. The wheels preferably have rubber tires 121, whichpress against surfaces 122 on the underside of each truck to force therollers 49 on the truck against the inside face of intumed am 45 ofretainer member 43, see FIGS. 4 and 6. In this manner, the trucks areheld in spaced-apart relationship as they move down the semicircularsection 34 of the cam path and are prevented from rolling freelydownward toward the return section of the path. Similar wheels 120having rubber tires [21 are used at the end of the return section tocarry each truck up to the top straight section. The trucks 47 areforced along the return section of the path in butted relation by wheels120 frictionally engaging the truck just entering the return section. Asshown in FIG. 7, each pair of wheels 120 and 120 are driven by the motorM; which is connected through gearbox 78 to shaft 125 on which wheels120' are mounted, and is also connected through shaft 79, gearbox 80,shaft 126, gearbox 127 to a shaft 128 on which the wheels 120 aremounted. The pairs of wheels 120 and 120 are of the same size and thedrive for them is such that they will be rotated in the same directionand at a rate commensurate with the rate at which the trucks are movedalong the top straight section of the conveyor path.

As mentioned above, the several webs and/or other parts to be assembledare held by vacuum in proper superposed relation on the bed of thetrucks 47 as they move along the top straight section of the conveyorpath in butted relation. Referring again to FIGS. 1 and 2, it will beappreciated that in assembling the composite article used for purposesof illustration, vacuum must be applied to different regions of thetruck beds at different times and for different intervals. For example,looking at FIG. 4, vacuum must be initially applied to the left-handside of the bed of the trucks to hold the webs l and 11' in superposedrelation on the trucks. Vacuum must be applied in this area from thetime these two webs are deposited on the trucks and for an interval ittakes for them to move under sealing roller 21 at which time these twowebs are sealed together by seal 13, see FIG. I. As the trucks 47approach the point where the web is layed down on top of web 11' vacuummust be applied to that region of the truck beds covered by web 15 andshould be maintained long enough to hold this web in proper superposedrelation with web 11' until sealing rollers 22 are passed and the web15' is attached to the web 11' by seals 16 and 17. Thereafter. vacuummust be applied to that region of the truck beds on which web 12' isdeposited, and should be maintained at least until sealing roller 23 ispassed and web 12' is sealed at 14 to web 11'. To be sure that web 12'is sealed to web 1 l' in proper superposed relation, it might bedesirable to hold either of the webs 10' or 11 or both, onto the truckby vacuum until web 12' is deposited and sealed to web 12'.

For applying vacuum to different regions of the truck beds at differenttimes and for selective intervals the following structure is used. Theends of the trucks facing the front of the conveyor, the right-hand endsthereof looking at FIG. 4, overhang or extend beyond, the front camtrack 30. The lower face 130 of this extension of the trucks, called theporting face, is provided with two or more porting holes arranged inlaterally spaced rows. As shown in FIGS. 4 and 5, the porting face 130of each truck may have five porting holes, one of which is designated131, two of which are designated 132, and the remaining two of which aredesignated 133. The two porting holes 133 are arranged in one rowextending longitudinally of the top straight section of the conveyorpath, the two porting holes 132 are arranged in another row laterallyspaced from the row of holes 133, and hole 131 is laterally spaced fromthe row of holes 132. Each of these holes is connected by appropriatecoring to a different area or region of the bed of the truck 47. Tofacilitate coring of the trucks 47, the bed 51 is made as a separatepiece from the truck body and the truck face is routed out as shown inFIG. 11 where the left-hand truck 47 is shown with its bedplate removedand the adjacent truck 47 has the bedplate in place and shows the vacuumholes entering different regions thereof. Porting holes 133 are eachconnected with corings 133', porting holes 132 are each connected withcorings 132', and porting hole 131' is connected with coring 131'.

Referring to FIG. 11, that portion of the truck beds 51 on which web 10is to be deposited is provided with an L-shaped array of holes 131"extending therethrough and adapted to communicate with the coring 131'.The hole 131" nearest the center of the truck beds which is adapted toalign with hole 25 in the web 11, (FIG. 1) so that vacuum can actthrough web 10 to hold the web 11' on top of the web 10', is shownembraced by a D-shaped depression 135. This depression is provided inthe event the hole 25 in the web 10' takes the form of moon slit, aspreviously mentioned, so as to allow the hinged flap formed by the moonslit to be pulled out of the plane of the web and open the hole to allowvacuum to pass through web 10' and act to hold down web 11.

That portion of the truck beds on which the narrow web 15' is to bedeposited is provided with two longitudinally spaced rows of holes 132"communicating with the corings 132. These holes align with holes 26 inthe web 11 to hold the web 15 down on web 11 (see FIG. 1) and are shownembraced by D-shaped depressions in the event holes 26 in web 11 are inthe form of moon slits as mentioned above.

That portion of the truck beds on which the web 12' is to be depositedis provided with two spaced rows of perforations 133" communicating withthe corings 133 to hold the web 12 on the truck bed in overlappingrelation with the end of web 11', see FIGS. land 4.

A stationary vacuum manifold extends almost the full length of the topstraight portion 32 of the conveyor path and is located so that theporting faces 130 of the trucks move in close proximity to the portingface 141 of the manifold. The vacuum manifold is evacuated through apipe 142 connected to a suitable exhaust fan, not shown. Threelongitudinal slots 143, I44 and 145 are aligned with, and embrace, theporting holes 131, 132, and 133, respectively, in the porting faces ofthe trucks, and each of these slots is placed in communication with theinterior of the vacuum manifold by a series of bores 146. Thus, as eachtruck moves along the straight top section 32 of the conveyor vacuum isapplied to the various regions of the truck bed 51, the timing beingcontrolled by the location and length of the different slots 143, 144,and 145 in the porting face of the vacuum manifold. In order to makethis conveyor system readily adaptable to the assembly of differentcomposite parts, rather than limited to the assembly of one particularone, the slots 143, 144, and 145 would initially be made to extend thefull length of the manifold, and plugs, not shown, could be insertedinto the different slots to vary the location and effective length ofthe slots to obtain any desired timing of the start and duration of thevacuum applied to the different regions of the truck beds.

The clearances between the porting faces 130 of the trucks 47 and theporting face 141 of the manifold must be very small, e.g. 0.0005-0.002inch, in order to efficiently transmit the vacuum to the truck beds. Ifforeign particles such as dust, enters this space, damage to, or gallingof, the porting face of the trucks and manifold may occur. Entry of suchforeign particles into this region is prevented in the following manner.The porting faces 130 and 141 of the truck 47 and manifold 140,respectively, are somewhat larger than required to accomplish the vacuumporting. 1n the regions embracing the vacuum slots 143, 144, and 145 onthe porting face 141 of the vacuum manifold, means are provided tosupply clean air in a quantity larger than that required to make upleakage into the porting area. As shown, particularly in FIGS. 4 and 11,this means of supplying clean air is through porous plastic inserts 150extending along the porting face 141 of the vacuum manifold in embracingrelation to the vacuum slots 143, 144, and 145. Air under pressure isforced up to the porting face of the manifold through these porousplastic inserts 150 from compressed-air plenums 151 connected bypipelines 152 to a suitable air compressor means, not shown. To preventthe air entering the space between the porting faces of the trucks andthe vacuum manifold from being drawn into the vacuum manifold, andthereby cutting down on the effectiveness of the vacuum applied to thetruck beds, slots 155 extend longitudinally along the porting face 141of the manifold between the porous plastic inserts 150 and the vacuumslots 143 and 145. These slots 155 are connected to the atmospherethrough a plurality of right angle bores 156 so that any air exitingfrom the porous plastic inserts 150 which tends to be drawn into thevacuum manifold will first have an exit to the atmosphere through theslots 155 and their associated bores 156.

From the above description, it will be apparent that each truck 47 mustbe kept tightly butted against the preceding truck as the trucks moveacross the vacuum manifold 140, for otherwise vacuum leakage would occurand the vacuum holding power of the truck beds would be inefficient.This means that the longitudinal faces of the individual trucks 47 mustbe machined carefully so that they will mate accurately when broughtinto abutment. This also points up the importance of the tendency driverolls 57 having sufficient driving power to bring each truck into tightabutment with the one ahead of it before the butted trucks are engagedby the first set of metering screws 75. After the trucks 47 are engagedby the metering screws 75, they will be maintained in tight abutmentthroughout their travel along the top straight portion of the conveyorby reason of the engagement of the screws 75 and 76 with the partialnuts 90 carried by each truck. Should the length of the top straightsection be relatively short, so that there are not too many trucks 47between the tendency drive and the second set of screws 76 to overloadthe tendency drive, then the first set of metering screws 75 could beeliminated as set forth above.

Should it be found necessary or desirable that the heat-sealing rollers21, 22, and 23 work against a resilient surface in order to produce theheat seals 13, 14, 16, and 17, then the beds 51 of the trucks 47 couldbe recessed in these regions and have sheets of rubber, or othersuitable resilient material, inserted in such recesses to be flush withthe remainder of the top of the truck beds. In FIG. 11 such rubberinserts are shown on the second truck from the left, the one undersealing roll 21 being indicated as at 160, the one under sealing rolls22 being indicated at 161, and the one under sealing roll 23 beingindicated at 162. To facilitate removal of the assembled composite webfrom the truck beds as thy reach the end of the top straight portion ofthe conveyor, that end of the truck beds above the porting face isprovided with three laterally spaced grooves (see FIGS. 4 and 11), intowhich stationary stripping fingers, not shown, located at the end of thestraight portion might extend to strip the assembled composite web fromthe truck beds so that it can be fed further onto a windup station, orthrough a chopping station where it is chopped up into individualcomponents of desired widths.

It is believed that from the above description it will be understoodthat this vacuum truck system meets all of the requirements of aconventional vacuum roll without possessing the limitations thereof. Themain advantage of this vacuum truck system is the top straight line pathfeature with the ability to hold materials on a rigid surface by vacuum.This allows two or more continuous webs, or discrete parts, to beregistered and sealed to each other without developing a differentiallength condition which will become apparent as a wrinkling of one webwhen the two are straightened out. Discrete parts which will not conformto an arcuate surface can be applied in registration with a web and beretained by vacuum until sealed in place by external means using thisvacuum truck system, whereas such an operation would be difficult, ifnot impossible, using a vacuum roll of practical dimensions. inaddition, this vacuum truck system is particularly suitable forcontinuous motion high-speed assembly machinery.

This invention has been described in detail with particular reference toa preferred embodiment thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention as described hereinabove as defined in the appendedclaims.

We claim:

1. A conveyor mechanism for continuous moving articles along arectilinear path at a given rate of speed while supporting them on arigid, flat surface comprising in combination:

1. an endless track having a straight portion coextensive with andparallel to said rectilinear path;

2 a plurality of trucks arranged in a row on said track and individuallymovable along said track, each truck having a flat bed arranged todefine a portion of said rectilinear path as the trucks move along saidstraight portion of said track;

3. means for driving said trucks around said track and including:

a. first drive means at the leading end of said straight portion forforcing the bed of each truck into butted relation with the bed of thetruck immediately ahead of it as the trucks move into said straightportion, and

b. second drive means for advancing the trucks in butting relation alongthe length of said straight portion at said given rate of speed.

2. A conveyor mechanism as defined in claim 1, wherein said first drivemeans comprises a tendency drive which tends to drive said trucks fasterthan said given rate of speed, and wherein said second drive meanscomprises a positive drive engaging said trucks after they have beenbrought into butting relation and metering their rate of travel alongthe remainder of the straight portion of said track.

3. A conveyor mechanism as defined in claim 2 wherein said positivedrive for the trucks comprises a rotatable metering screw extendingalong the straight portion of said track, and a threaded partial nut oneach truck adapted to be brought into mating engagement with said screwafter the trucks have been moved into butting relation by said tendencydrive.

4. A conveyor mechanism as defined in claim 2 wherein said positivedrive for the trucks comprises two like rotatable metering screwsextending along the straight portion of said track in spaced coaxialrelation adapted to be successively engaged by the threaded partial nutson the trucks, means for mounting the metering screw nearest thebeginning of the straight portion of the track for a limited axialmovement relative to said other metering screw to allow the beds of theseries of trucks between said two screws to be held in butting relationdespite tolerable variations in the dimensions of said truck beds in thedirection of their movement.

5. A conveyor mechanism according to claim 1 wherein said endless trackincludes a return section located vertically below said straight portionwhich is connected to the leaving end of said straight portion by anarcuate portion, and wherein said means for driving said trucks aroundsaid track includes a third drive means for moving said trucks throughsaid arcuate portion in spaced relation and pushing said trucks alongsaid return section with their beds in butted relation.

6. A conveyor mechanism according to claim 5 wherein said return sectionof the track is connected to the beginning of the straight portionthereof by a second arcuate portion, and wherein said means for drivingsaid trucks around said track includes a fourth drive means for movingthe trucks, as they reach the end of said return section, up said secondarcuate portion to the beginning of said straight section.

7. A vacuum conveyor mechanism for moving two or more webs and/ordiscrete articles along a rectilinear path at a given rate of speedwhile holding them in a predetermined superimposed relation on a rigid,flat surface comprising in combination:

1. an endless track having a straight portion coextensive with andparallel to said rectilinear path;

2. a plurality of trucks supported in a row on said track andindividually movable along said track, each truck including:

a. a flat bed arranged to define a portion of said rectilinear path asthe trucks move along said straight portion of said track;

3. means for driving said trucks around said track, and including:

a. first drive means at the leading end of said straight portion forforcing the bed of each truck into butting relation with the bed of thetruck immediately ahead of it, as the trucks move into said straightportion, to form a rigid, flat surface on which said webs and/ordiscrete articles are adapted to be deposited in sequence and inoverlapping relation;

b. second drive means for advancing the trucks in butting relation alongthe length of said straight portion at a given rate of speed; and

4. means for applying a vacuum to different areas of the truck beds atdifferent intervals as the trucks move along said straight portion tohold the webs and/or discrete elements on the butted truck beds in thesuperimposed relation they are deposited thereon.

8. A vacuum conveyor mechanism as defined in claim 7 wherein saidlast-mentioned means includes:

1. a porting face in the bottom of each truck provided with an (n)number of porting holes laterally spaced relative to the direction ofmovement of said trucks;

2. different regions of the bed of each truck provided with holes;

3. conduits in each truck placing the holes common to a certain regionof the bed in communication with a different one or group of saidporting holes,

4. a stationary vacuum manifold below and parallel to said straightportion of the track and having a porting face in close proximity withwhich the porting faces of said trucks move as they move along saidstraight section,

5. an (n) number of elongated ports through the porting face of saidmanifold arranged so that each one thereof is aligned with a differentone or group of the porting holes in the porting face of said trucks asthe trucks move over the manifold, whereby the timing of the applicationof vacuum to the various regions of the truck beds is controlled by thelocation and length of the ports in the porting face of the vacuummanifold. I I 9. A vacuum conveyor mechanism as defined in claim 8, in-

cluding means for preventing foreign particles from being drawn into thespace between the porting faces of said trucks and said vacuum manifoldby the vacuum in this space.

10. A vacuum conveyor mechanism as defined in claim 9, wherein saidlast-mentioned means includes means for supply ing clean air underpressure to the regions bounding the ports in the porting face of saidvacuum manifold in a quantity larger than that required to make upleakage into the porting area.

1. A conveyor mechanism for continuous moving articles along arectilinear path at a given rate of speed while supporting them on arigid, flat surface comprising in combination:
 1. an endless trackhaving a straight portion coextensive with and parallel to saidrectilinear path;
 2. a plurality of trucks arranged in a row on saidtrack and individually movable along said track, each truck having aflat bed arranged to define a portion of said rectilinear path as thetrucks move along said straight portion of said track;
 3. means fordriving said trucks around said track and including: a. first drivemeans at the leading end of said straight portion for forcing the bed ofeach truck into butted relation with the bed of the truck immediatelyahead of it as the trucks move into said straIght portion, and b. seconddrive means for advancing the trucks in butting relation along thelength of said straight portion at said given rate of speed.
 2. aplurality of trucks arranged in a row on said track and individuallymovable along said track, each truck having a flat bed arranged todefine a portion of said rectilinear path as the trucks move along saidstraight portion of said track;
 2. A conveyor mechanism as defined inclaim 1, wherein said first drive means comprises a tendency drive whichtends to drive said trucks faster than said given rate of speed, andwherein said second drive means comprises a positive drive engaging saidtrucks after they have been brought into butting relation and meteringtheir rate of travel along the remainder of the straight portion of saidtrack.
 2. a plurality of trucks supported in a row on said track andindividually movable along said track, each truck including: a. a flatbed arranged to define a portion of said rectilinear path as the trucksmove along said straight portion of said track;
 2. different regions ofthe bed of each truck provided with holes;
 3. conduits in each truckplacing the holes common to a certain region of the bed in communicationwith a different one or group of said porting holes,
 3. means fordriving said trucks around said track, and including: a. first drivemeans at the leading end of said straight portion for forcing the bed ofeach truck into butting relation with the bed of the truck immediatelyahead of it, as the trucks move into said straight portion, to form arigid, flat surface on which said webs and/or discrete articles areadapted to be deposited in sequence and in overlapping relation; b.second drive means for advancing the trucks in butting relation alongthe length of said straight portion at a given rate of speed; and
 3. Aconveyor mechanism as defined in claim 2 wherein said positive drive forthe trucks comprises a rotatable metering screw extending along thestraight portion of said track, and a threaded partial nut on each truckadapted to be brought into mating engagement with said screw after thetrucks have been moved into butting relation by said tendency drive. 3.means for driving said trucks around said track and including: a. firstdrive means at the leading end of said straight portion for forcing thebed of each truck into butted relation with the bed of the truckimmediately ahead of it as the trucks move into said straIght portion,and b. second drive means for advancing the trucks in butting relationalong the length of said straight portion at said given rate of speed.4. A conveyor mechanism as defined in claim 2 wherein said positivedrive for the trucks comprises two like rotatable metering screwsextending along the straight portion of said track in spaced coaxialrelation adapted to be successively engaged by the threaded partial nutson the trucks, means for mounting the metering screw nearest thebeginning of the straight portion of the track for a limited axialmovement relative to said other metering screw to allow the beds of theseries of trucks between said two screws to be held in butting relationdespite tolerable variations in the dimensions of said truck beds in thedirection of their movement.
 4. means for applying a vacuum to differentareas of the truck beds at different intervals as the trucks move alongsaid straight portion to hold the webs and/or discrete elements on thebutted truck beds in the superimposed relation they are depositedthereon.
 4. a stationary vacuum manifold below and parallel to saidstraight portion of the track and having a porting face in closeproximity with which the porting faces of said trucks move as they movealong said straight section,
 5. an (n) number of elongated ports throughthe porting face of said manifold arranged so that each one thereof isaligned with a different one or group of the porting holes in theporting face of said trucks as the trucks move over the manifold,whereby the timing of the application of vacuum to the various regionsof the truck beds is controlled by the location and length of the portsin the porting face of the vacuum manifold.
 5. A conveyor mechanismaccording to claim 1 wherein said endless track includes a returnsection located vertically below said straight portion which isconnected to the leaving end of said straight portion by an arcuateportion, and wherein said means for driving said trucks around saidtrack includes a third drive means for moving said trucks through saidarcuate portion in spaced relation and pushing said trucks along saidreturn section with their beds in butted relation.
 6. A conveyormechanism according to claim 5 wherein said return section of the trackis connected to the beginning of the straight portion thereof by asecond arcuate portion, and wherein said means for driving said trucksaround said track includes a fourth drive means for moving the trucks,as they reach the end of said return section, up said second arcuateportion to the beginning of said straight section.
 7. A vacuum conveyormechanism for moving two or more webs and/or discrete articles along arectilinear path at a given rate of speed while holding them in apredetermined superimposed relation on a rigid, flat surface comprisingin combination:
 8. A vacuum conveyor mechanism as defined in claim 7wherein saId last-mentioned means includes:
 9. A vacuum conveyormechanism as defined in claim 8, including means for preventing foreignparticles from being drawn into the space between the porting faces ofsaid trucks and said vacuum manifold by the vacuum in this space.
 10. Avacuum conveyor mechanism as defined in claim 9, wherein saidlast-mentioned means includes means for supplying clean air underpressure to the regions bounding the ports in the porting face of saidvacuum manifold in a quantity larger than that required to make upleakage into the porting area.